Trends in physical properties at the southern New England shelf break

Abstract

We analyze 11 years (2003–2013) of repeat temperature and salinity sections from across the New England shelf break south of Cape Cod during early summer (June–July). The mean sections resolved the shelf break front which supports the Shelf Break Jet, a vital component of the regional circulation. Individual sections showed a great deal of variability associated with meanders in the shelf break front consistent with previous studies in the region. Over the 11 year record, the shelf region (inshore of the 100 m isobath) warmed by 0.26 °C yr -1, with the majority of this warming occurring shallower than 20 m (0.58 °C yr -1). The full‐depth trend agrees well with previous studies of shelf warming to the north and the south of our study region. The temperature and salinity of the offshore edge of the Cold Pool Water on the shelf did not change significantly during this period. The surface warming on the shelf resulted in a decrease in near‐surface density of 0.12 kg m -3 yr -1 and an increase in stratification between 10 and 15 m of 6.7 X 10(-5) S -2 yr -1 . Offshore of the shelf break, the Slope Water also warmed and became more saline by 0.21 °C yr -1 and 0.04 yr -1 respectively, resulting in a maximal reduction in density of 0.01 kg m -3 yr -1. In the Shelf Break Front, there is some evidence of freshening and a reduction in density, which may have resulted from an offshore shift in the Cold Pool but the statistical significance is small.